Page 120 - New Medley 4 Semester 1

They did not use place value system. There is no symbol to write 0 in the Roman
Numeral System. They formed the numbers 1 to 39 using just three symbols

I, V and X.

Let us know the rules they followed to write the numbers and hence extend
writing numbers up to 100.

Rule 1: If a smaller numeral is written after a larger numeral, their values

are added.

Examples: VI = 5 + 1 = 6, XV = 10 + 5 = 15,

XI = 10 + 1 = 11 and LX = 50 + 10 = 60

Rule 2: If a smaller numeral is written before a larger numeral, its value

is subtracted from the value of the larger numeral.

Examples: IV = 5 – 1 = 4, XL = 50 – 10 = 40 and IX = 10 – 1 = 9

Note: V and L never come before a larger numeral and hence
they cannot be subtracted. I can come before V and X, and X

can come before L and C only.

Rule 3: If a numeral is repeated, it means addition. Any symbol can be
repeated maximum up to 3 times.

Examples: II = 1 + 1 = 2, III = 1 + 1 + 1 = 3,

XX = 10 + 10 = 20 and CCC = 100 + 100 + 100 = 300

Note: V and L can never be repeated.

Rule 4: If a smaller numeral is placed between two larger numerals, the
value of the smaller numeral is always subtracted from the value

of the larger numeral following it.

Examples: XIV = 10 + (5 – 1) = 10 + 4 = 14

XIX = 10 + (10 – 1) = 10 + 9 = 19

LIX = 50 + (10 – 1) = 50 + 9 = 59

XLIX = (50 – 10) + (10 – 1) = 40 + 9 = 49

118